Changing colour images to B&W often has surprising results.
You may not get what you expected. Often this is because the contrast in colour shots is quite low. B&W conversion requires contrast to work well. This is how you can increase the contrast…
We are trying to increase the range of greyscale tones in the picture. Grey is a fickle colour – it fades from tone to tone almost unnoticed. In a high contrast shot we want to stretch the grey and express tones from deep blacks to whitest whites. This is something we avoid in colour because deep black or blown-out white is a distraction. In black and white they can be too, but if well controlled the balance helps emphasise the pictures’ strong elements. So we must add the contrast. That can be done by applying one or more techniques in post-processing:
- Add deeper tones to the darker areas, whites to the lighter areas
- Create darker/lighter tones over the whole image – moody effect
- Use an overlay technique to apply contrast
I am not going to go into depth with these. Just some simple ideas.
Add deeper tones to the darker areas, whites to the lighter areas
You can do the same for whites with the ‘Dodge’ tool. Select ‘highlights’ and a low ‘exposure’ then paint over bright areas and they will brighten slightly. Higher exposures brighten more. Set the tool for shadow and you can lighten darker areas.
In both tools ‘mid-tone’ will brighten or darken the mid-range tones depending on which tool you are using.
Create darker tones over the whole image – moody effect
You can use a ‘contrast’ control in most image editors to affect the lightness and darkness proportions across the image. However, too much of this control tends to give sickly greys an outing. Faces especially look ill if you apply too much of the contrast control.
In most image editors there is usually a ‘gamma’ control somewhere. This uniformly affects the blacks right across the image. Often the toning down of blacks is enough to shift the image to the moody or dramatic side. Gamma gives you great control over this. So look up in your help files how to adjust your Gamma.
In Photoshop the control is in the exposure adjustments panel. If you have not got gamma control in your editor you can use it in Irfanview (free download). Irfanview has a great gamma control. You can find both gamma and contrast with other colour controls in the menus. Go to Image; Colour Corrections… The dialoge box there is worth playing around with.
Gamma is not so good for adding brightness, but in small measure it is OK. So you can either whiten or darken the image using the gamma setting. It actually is great for toning down all sorts of white errors.
Use an overlay technique to apply contrast
In the image editing applications that use layers and overlay there are literally hundreds of ways to adjust contrasts. I have seen one ‘grunge’ technique use 16 layers and 35 steps to create a contrast-widening effect. While grunge is a popular look in image processing it is an artistic process that you really need to practice a lot before it is effective. And, like many processes can be overdone. So, to help you out I have researched the technique below. It is quick and easy. It is possible in several of the full blown applications for image editing. Best of all it takes a few seconds to apply and you can see the results straight away. So watch this short video and I bet you will be itching to have a go…
Uploaded by Larry Lourcey on Dec 16, 2010 http://www.PhotoEducationOnline.com
An important note…
Remember that all of these techniques work better in RAW. Attempting to use them in .jpg is a lost cause and may just look a mess. Although, to be fair, that does depend on the image. Take my advice and shoot in RAW. For 99.8% of the time the results will be better after processing. Remember not to do post processing on your only image. Keep an original and only work on copies.